Well, you didn't have to until this bug cropped up recently. The webhook config is supposed to be editable! So you should open a case if you get a chance, need more pressure for a fix.
Glad this was resolved. Sometimes I run into issues when the response isn't mapped using an index value for the vector... Your JSON response isn't configured this way, but if there were no "response" array title, it's valid to have "[0].id" that would write the value 2 to whatever Marketo field you mapped that to...
Just food for thought for response mapping issues...
Yep, we use this on another web hook. Can't remember where i stumbled on the [0].key idea but it works very well.